Maybe it’s not a good idea to sign minor leaguers to long-term contracts.

General manager Jeff Luhnow is invested in both youngsters; he signed Singleton to a five-year, $10 million contract last June, and acquired Marisnick from the Marlins last July 31 in the six-player Jarred Cosart trade. But the Astros, acting on a mandate from owner Jim Crane, also are trying to improve quickly, as evidenced by their active offseason and increase in payroll.